Download intraoperative awakening for vision examination during ophthalmic

INTRAOPERATIVE AWAKENING FOR VISION EXAMINATION
DURING OPHTHALMIC ARTERY ANEURYSM CLIPPING:
TECHNICAL CASE REPORT
Peng Chen, M.D.
Cerebrovascular Center,
Department of Neurosurgery,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Ian F. Dunn, M.D.
Cerebrovascular Center,
Department of Neurosurgery,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Linda S. Aglio, M.D.
Department of Anesthesiology,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Arthur L. Day, M.D.
Cerebrovascular Center,
Department of Neurosurgery,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Kai U. Frerichs, M.D.,
Ph.D.
Cerebrovascular Center,
Department of Neurosurgery,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Robert M. Friedlander,
M.D., M.A.
Cerebrovascular Center,
Department of Neurosurgery,
Brigham and Women’s Hospital,
Harvard Medical School,
Boston, Massachusetts
Reprint requests:
Robert M. Friedlander, M.D.,
Department of Neurosurgery,
Brigham and Women’s Hospital,
75 Francis Street,
Boston, MA 02115.
Email:
[email protected]
Received, September 11, 2003.
Accepted, July 22, 2004.
OBJECTIVE AND IMPORTANCE: We present a case of a patient with an ophthalmic
artery aneurysm in which the ophthalmic artery originated from the body of the
aneurysm, requiring sacrifice of the ophthalmic artery to achieve complete aneurysm
obliteration. We awakened the patient intraoperatively to assess optic nerve function
after clipping and were able to confirm optic nerve function. Controlled intraoperative
awakening proved a valuable adjunct to intraoperative angiography in determining the
immediate consequences of sacrifice of the ophthalmic artery.
CLINICAL PRESENTATION: The patient was a 55-year-old right-handed woman with
a 3-month history of episodic blurriness in her left eye; imaging demonstrated an
unruptured 5-mm left ophthalmic artery aneurysm in which the ophthalmic artery
originated from the body of the aneurysm.
INTERVENTION: Complete obliteration of the aneurysm required clip placement across
the neck of the aneurysm, incorporating not only the aneurysm but also the ophthalmic
artery. Aware that sacrifice of the ophthalmic artery was likely, we awakened the patient
after clipping and before dural closure to evaluate her optic nerve function. Once fully
awake, the patient was able to execute simple commands and conclusively confirm light
perception in both of her eyes. She was then reanesthetized, and intraoperative angiography showed successful aneurysm obliteration and parent artery patency.
CONCLUSION: The ophthalmic artery can be sacrificed during aneurysm clipping without loss of vision in many cases, most likely because of adequate collateral filling from the
external carotid artery. Certainty about the visual consequences of sacrifice of the ophthalmic artery, however, is difficult to obtain preoperatively or intraoperatively. Intraoperative awakening for evaluation of optic nerve function served as a useful technique to
assess the acute results of interruption of ophthalmic artery flow in this case.
KEY WORDS: Intraoperative awakening, Ophthalmic aneurysm, Ophthalmic artery
Neurosurgery 56[ONS Suppl 2]:ONS-440, 2005
W
hen clipping ophthalmic artery aneurysms, the surgeon must sometimes sacrifice the ophthalmic artery to obtain complete obliteration of the
aneurysm. In most cases, anastomoses from
the external carotid artery circulation are adequate to reconstitute the ophthalmic artery
territory. Although angiographically proven
retinal collateralization is often evident in
such cases, there is still some uncertainty as to
whether radiographic restoration equates to
functional visual preservation. We present a
case of an ophthalmic artery aneurysm in
which the origin of the ophthalmic artery was
incorporated into the body of the aneurysm
and was sacrificed by clip placement. We used
controlled intraoperative awakening directly
ONS-E440 | VOLUME 56 | OPERATIVE NEUROSURGERY 2 | APRIL 2005
DOI: 10.1227/01.NEU.0000156846.61123.79
after clip placement before closing of the dura
and before intraoperative angiography to examine the patient’s visual fields, which confirmed functional visual preservation.
CASE REPORT
History
This 55-year-old right-handed woman was
referred for neurosurgical evaluation after experiencing four episodes of blurry vision in
her left eye over the preceding 3 months. Each
episode was accompanied by a sensation of
“heaviness” in her head and lasted between 15
and 20 minutes. She reported no visual problems between these events. She was otherwise
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INTRAOPERATIVE AWAKENING
healthy, with the remainder of her medical history remarkable
for her mother having had an intracerebral aneurysm of unknown type.
Examination
Neurological examination was normal, revealing full extraocular movements of both eyes and no deficits in Cranial
Nerves II to XII. The pupils were equally reactive, and her
visual fields were full to confrontation with no quadrant deficits and good acuity and no reported diplopia. The remainder
of her physical examination was unremarkable.
Cranial magnetic resonance imaging showed an approximately 5-mm ophthalmic artery aneurysm displacing the optic
nerve. Catheter-based angiography demonstrated a 5-mm left
ophthalmic artery aneurysm pointing superiorly, with a 4-mm
neck and with the ophthalmic artery origin incorporated into
the body of the aneurysm (Fig. 1).
Operation and Intraoperative Awakening
The risks of clipping the aneurysm, including potential loss
of vision in her left eye after sacrifice of the left ophthalmic
artery, were fully explained. The patient was particularly concerned about the possible risk of monocular blindness. Preoperative discussion resulted in a plan of intraoperative awakening for functional evaluation of her vision. If loss of vision
was evident after clipping, the clip would be backed up to
reestablish ophthalmic artery flow. The patient understood
the consequences of harboring an aneurysmal remnant. We
considered preoperative balloon test occlusion but decided
that the risk of aneurysm rupture during occlusion, given the
incorporation of the artery in the aneurysm, was an unacceptable risk. She thus elected to proceed with surgical treatment,
with an intraoperative awakening technique developed to
evaluate vision directly after clipping of the aneurysm. Anesthesia was induced in a standard manner with nitrous oxide,
thiopental, and vecuronium, and the patient was maintained
on a combination of remifentanyl and intermittent pancuronium and fentanyl. We planned on using intraoperative visual
FIGURE 1. Angiogram showing preoperative left internal carotid artery
injection (A) demonstrates an ophthalmic artery aneurysm with the origin
of the left ophthalmic artery in the body of the aneurysm (white arrow).
B, three-dimensional angiography more clearly shows the left ophthalmic
artery originating from the body of the aneurysm (white arrow).
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evoked potentials but found that the anteriorly projecting
craniotomy skin and muscle flap interfered with correct
equipment positioning and thus proceeded without this monitoring. During surgery, the ophthalmic artery was clearly
seen to originate from the body of the aneurysm. A sideangled Aesculap clip (Aesculap Co., Tuttlingen, Germany)
was easily placed at the base of the aneurysm, incorporating
the ophthalmic artery origin. After clip placement, the anesthesia was reversed with neostigmine, glycopyrrolate, and
nalbuphine, at which time the patient began breathing spontaneously and moving all extremities. She was asked to show
her right thumb on two occasions, and she followed these
commands easily. She was then instructed to hold up the same
thumb if she could see light being shined into her left and
right eyes alternately. She responded briskly on each occasion
to clearly indicate her light perception; the contralateral eye
was carefully covered so as not to affect the examination. We
were thus satisfied that her vision had been at least grossly
preserved after clipping, and she was reanesthetized with a
combination of sevoflurane, nitrous oxide, and remifentanyl.
The duration of intraoperative awakening was 20 minutes,
and no complications occurred.
An intraoperative angiogram then demonstrated complete
obliteration of the aneurysm and patency of the internal carotid artery, with no filling of the left ophthalmic artery.
Reconstitution of the left retinal choroidal blush was observed
on injection of the left external carotid artery (not shown). The
dura and tissue layers were then closed in the standard
manner.
Postoperative Course
Postoperatively, the patient had full vision in both eyes. She
had an uneventful hospital course and was discharged on the
third postoperative day. A formal postoperative angiogram
obtained before discharge demonstrated complete aneurysm
obliteration (Fig. 2A) and a choroidal blush supplied by
branches of the left external carotid artery (Fig. 2B). One year
later, she continues to have full vision. It is of interest to note
that, after surgery, she has not had a recurrence of the left eye
blurriness that she described before surgery.
FIGURE 2. A, angiogram showing postoperative injections of the left
common carotid artery in the later phase showing obliteration of the aneurysm and no flow in the left ophthalmic artery. B, late-phase left external
carotid artery injection demonstrating the retinal choroidal blushing supplied by branches of the external carotid artery (white arrow).
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CHEN
ET AL.
DISCUSSION
Visual loss after disruption of ophthalmic artery flow may
result from insufficient vascular supply to the retina from the
collateral circulation or from interference with small branches
to the optic nerve arising near the point of occlusion. Named
branches from the ophthalmic artery include the central retinal, anterior falcine, ethmoidal, ciliary, and recurrent meningeal arteries. The muscular and extraorbital branches of these
vessels anastomose extensively with numerous branches from
the external carotid artery (8). Under most circumstances, it is
possible to rely on reversal of flow through these functional
anastomoses to supply the visual system after ophthalmic
artery occlusion. These connections account for the virtual
lack of retinal strokes associated with internal carotid artery
occlusions.
Despite arteriographic evidence of extensive anastomoses,
however, intentional sacrifice of the ophthalmic artery causes
some uncertainty as to whether vision will be compromised.
The patient in this case favored surgical intervention for clip
obliteration of her aneurysm but nevertheless continued to
voice significant concern over the possibility of visual deterioration. Preoperative management options in this scenario
included performing a balloon test occlusion across the neck
of the aneurysm to assess the functional consequences of
sacrifice of the ophthalmic artery during surgery. With the
current state of technology, balloon test occlusion in a case
such as this, in which sacrifice of the aneurysm may have
significant neurological sequelae, is commonly performed,
and the feasibility of ophthalmic artery balloon test occlusion
has been described, with advantages including the assessment
of appropriate collateral filling of the retinal choroid during
interruption of ophthalmic arterial flow (6, 7). We weighed
this benefit against the risks of balloon test occlusion in this
case. In this particular patient, the aneurysm was on the left,
and test occlusion there carries with it the risk of global
aphasia and/or hemiplegia, which, if it occurred, would have
immediately ended the test, thereby not allowing sufficient
time for a conclusive vision test. In addition, the test occlusion
would have required an occlusive inflation, which is higher
than what is needed for coil-assist and increases the risk of
balloon intrusion into the neck of the aneurysm. We thus
decided against this preoperative maneuver, given these risks,
and elected to proceed directly to surgery with a plan to assess
gross visual preservation by intraoperative assessment of light
perception after aneurysm clipping. The timing of our intraoperative awakening examination before dural closure and
before intraoperative angiography was such that the aneurysm clip could have been repositioned should vision have
been compromised, in keeping with our patient’s stated
wishes that vision be preserved with or without complete
aneurysm obliteration.
Intraoperative awakening after clip placement, followed by
examination of optic nerve function at a point at which clip
repositioning could be executed, was at least a comforting
adjunct to intraoperative angiography in this case. At the same
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time, we could visualize the segment of the ophthalmic artery
to be sacrificed, so as to make sure that no small unnamed
branches supplying the optic nerve were incorporated into the
clip.
Intraoperative neurological assessment is common in tumor
surgery and some functional procedures (1, 2, 9) but is uncommon in aneurysm surgery. The Drake tourniquet has been
applied and then closed in awake patients during proximal
ligation of giant posterior circulation aneurysms (4, 5). To the
best of our knowledge, this is the first report of intraoperative
awakening for visual field assessment after clipping of an
ophthalmic artery aneurysm. In selected cases in which the
ophthalmic artery is incorporated into the body of the aneurysm and is to be intentionally sacrificed to achieve complete
aneurysm obliteration, variations of this method combined
with intraoperative angiography may provide valuable immediate feedback to facilitate a successful functional and anatomic outcome.
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4. Child CS, Heining MP, Calder I, Crockard HA: Anaesthesia for surgical
occlusion of the basilar artery: A technique involving intra-operative awakening to allow neurological assessment. Anaesthesia 41:191–194, 1986.
5. Drake CG: Giant intracranial aneurysm: Experience with surgical treatment
in 174 patients. Clin Neurosurg 26:12–95, 1979.
6. Ezura M, Takahashi A, Yoshimoto T: Combined intravascular parent artery
and ophthalmic artery occlusion for giant aneurysms of the supraclinoid
internal carotid artery. Surg Neurol 47:360–363, 1997.
7. Larson JJ, Tew JM Jr, Tomsick TA, van Loveren HR: Treatment of aneurysms
of the internal carotid artery by intravascular balloon occlusion: Long-term
follow-up of 58 patients. Neurosurgery 36:26–30, 1995.
8. Lasjaunias P, Berenstein A: Embryology and anatomy of the branches supplying the orbit, in Lasjaunias P, Berenstein A (eds): Surgical
Neuroangiography. New York, Springer, 2001, vol 1, pp 426–455.
9. Walsh AR, Schmidt RH, Martsh HT: Cortical mapping and local anaesthetic
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Neurosurg 6:119–124, 1992.
COMMENTS
C
hen et al. present a novel method of assessing vision
intraoperatively during clipping of a carotid-ophthalmic
artery aneurysm, in which deliberate sacrifice of the ophthalmic artery origin was deemed necessary. Other methods of
intraoperative functional monitoring, such as the use of somatosensory evoked potentials, brainstem auditory evoked
potentials, and motor evoked potentials, have considerable
usefulness for confirming intact sensory, auditory, and motor
pathways, but our experience at Stanford suggests that visual
evoked responses are not reliable in monitoring the visual
pathways, especially the retina, intraoperatively. Intraoperative wake-up tests are currently used during certain types of
spinal surgery, and awake craniotomies to map functional
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language areas are also frequently used. However, the use of
intraoperative awakening to assess vision is novel.
As the authors point out, the retina has luxuriant collaterals,
and usually, occlusion of the ophthalmic artery origin (either
surgically or endovascularly) is well tolerated, with no adverse visual consequences. Nonetheless, most cerebrovascular
surgeons have experienced the extremely rare, but very distressing, occurrence of unilateral visual loss or blindness after
clipping ophthalmic or paraclinoid artery aneurysms. In my
own practice, I have sometimes deliberately left a small residual aneurysm base so as to spare the ophthalmic artery origin
and preserve antegrade flow to the retina. Although it is not
clear that this technique of intraoperative awakening would
allow for more sophisticated visual fielding testing, it may be
quite useful in confirming gross vision, including light perception and movement.
Gary K. Steinberg
Stanford, California
T
he authors report a case in which a patient was awakened
intraoperatively for visual assessment. This vignette illustrates how individualized management decisions must be to
include not only patient safety, but also patient wishes. In this
case, adequate collateral existed to supply the ophthalmic
territory despite its being included in the clip occlusion. We
have had good luck in testing visual tolerance of ophthalmic
artery occlusion using nondetachable balloons. In our view,
this would be the first line of provocative testing in this kind
of patient, but the present treatment resulted in a successful
outcome.
Richard Parkinson
H. Hunt Batjer
Bernard Bendok
Chicago, Illinois
T
he authors describe a somewhat bold maneuver for evaluating retinal/ocular blood flow during aneurysm surgery
on ophthalmic segment lesions. In an effort to completely
occlude the aneurysm base, which inevitably involves occluding the ophthalmic artery, they propose awakening the patient
temporarily to assess light perception. My policy in this sort of
lesion has been to preserve the ophthalmic artery whenever
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possible. This may mean an occasional, purposeful adjustment
of the clip application to allow enough of the neck of the
aneurysm that is common to the origin of the ophthalmic
artery to remain so that the ophthalmic artery remains patent.
I am not aware of reports that this policy results in a substantial number of aneurysm recurrences. However, I would certainly not argue that complete occlusion of the neck of an
aneurysm, especially during direct surgery, is not the ideal.
Therefore, a more automated and potentially more reliable
assay of retinal blood flow would be valuable in this situation.
I have often wondered whether fluorescein angiography of the
retina could be assayed in a more quantitative way so as to be
used intraoperatively. Perhaps the use of the scanning laser
ophthalmoscope in conjunction with intraoperative intravenous fluorescein would be a way to gain a more objective
quantifiable assessment of retinal blood flow and might be
useful intraoperatively.
Steven Giannotta
Los Angeles, California
T
he authors present an interesting case in the treatment of
an ophthalmic artery aneurysm, in which they use a
wake-up test to assess vision in the patient’s eye and potentially modify their treatment on the basis of those results. They
were surgically managing a small, 5-mm ophthalmic artery
aneurysm in a patient who was symptomatic with intermittent
visual symptoms on the appropriate side. Weaknesses of the
wake-up test include the patient’s ability to assess only light
perception and an apparent preoperative decision to withdraw the clip slightly to maintain flow should the patient have
failed the vision test. Obviously, this would have left a residual aneurysm in a patient who is starting with a small aneurysm in the first place. Reasons for using the wake-up test
were justified in the article, whereby they excluded other
techniques that could have been performed preoperatively.
Interestingly, the authors have applied a well-known intraoperative assessment technique to cerebrovascular surgery.
We will need to consider this in our own treatment
armamentaria.
Philip E. Stieg
New York, New York
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